For the past several decades, the scaling of features in integrated circuits has been a driving force behind an ever-growing semiconductor industry. Scaling to smaller and smaller features enables increased densities of functional units on the limited real estate of semiconductor chips. For example, shrinking transistor size allows for the incorporation of an increased number of memory devices on a chip, lending to the fabrication of products with increased capacity. The drive for ever-more capacity, however, is not without issue. The necessity to optimize the performance of each device becomes increasingly significant.
Increase carrier mobility (beyond a carrier mobility of silicon) is desired to continue scaling transistor devices, including complementary metal oxide semiconductor (CMOS) inverters and to deliver increased performance and lower power. Promising materials such as group III-V compound semiconductor materials offer high electron mobility for n-channel metal oxide semiconductor field effect transistors (MOSFETs) and germanium based materials offer high hole mobility for p-channel MOSFETs. Because of differences between group III-V compound semiconductor materials and germanium materials, there are significant challenges integrating the two separate systems on silicon in a highly scaled CMOS inverters for sub-10 nanometers (nm) node geometries. Additionally, thin film stacks including buffer layers, gate stacks, contacts, etc. are expected to be different for group III-V compound semiconductors and germanium which further increases a complexity of integrating these different channel materials for scaled CMOS.